Adding a Rank Image below users avatar

First off I apologize if this has been asked and answered before. I spent the past half hour searching the forums, and while some people have similar questions, I didn’t really find anything that helped me with what I’m looking for. Its also early in the morning so I may just missed it. If thats the case just point me to the thread and delete this as you see fit.

Anyways I have two questions I could use some help with. First off, what I’m looking to do is add an image below the user avatar based either on their usergroup or their rank.

You can see an example on an existing forum I run here http://7kingdoms.net/pt/forum/index.php?topic=33.0
The Lord Chancellor, Earl Greyjoy, etc that you see under the avatars in that thread are the sorts of thing I want to be able to display under a users avatar (based on a usergroup, rank, or some other defined parameter I can set.) This is a feature that has been standard on every other forum software for years so I am sure there is someway to do it here, but unfortunately I can’t seem to figure it out.

Also I apologize if this is in the wrong sub-forum, but I assume there must be a plugin or something that can do this so I posted here (in fact there is a post from 5 years ago about a plugin that does what I ask, but the links in it are all dead).

To add a follow up question (not quite related but I don’t want to clutter the forums).

Is it possible to add a user legend to the bottom of the forum or web page (again, the only plugin I found that seems close to this gave me a 404).

As an example here is a forum I used to belong to that has one at the bottom of the page: Mostly Harmless Alliance Their legend is atrocious with how cluttered it is, but thats besides the point.

All online users are displayed at the bottom, with a list of all the usergroups on the forum displayed beneath. Each usergroup is set to that the persons nick will appear a different color when posting, but I should be able to figure out how to do that on my own (assuming its not built in to the existing usergroup plugins) as long as I can figure out how to get a legend.

Adding an image based on user rank is relatively easy to achieve…
Inside your theme files there is a file called loop-single-reply.php, you can find the author ID of the current reply and then from there get all the data for that user.